The invention relates to methods and apparatus for making and breaking electrical connection with electrical equipment such as transformers, switchgear, or cables.
Deadfront switchgear has been replacing livefront apparatus because of the safety, lower cost and increased operability of the deadfront system. Since there is no exposed voltage, safety is increased for both the operator and the public. In addition, the ability to operate easily and efficiently either with grounded, visible break connection points or loadbreak connection points by means of hotstick operation with a one or two man crew, lessens the operating danger. The deadfront system has proven to be extremely reliable with very low failure rate.
In practice, 600 ampere T-connectors have been used in these deadfront systems because they permit deadfront connection and visible disconnection by hotstick while the device is grounded. Visible disconnection is achieved by backing the T-connector off the 600 ampere bushing with a tool operated by a shotgun stick. One of the drawbacks to the use of T-connectors, however, is the bulky and stiff 600 ampere cable attached to the T-connector which makes it difficult to handle the T-connector.
It has also been proposed to interconnect T-connectors by means of a generally U-shaped member in which the legs of the "U" carry male contacts which connect with female contacts of the T-connectors. The legs are interconnected by a buss portion which includes means for connecting a ground wire and provides access to a threaded actuator in each leg for applying the U-member to the T-connectors. This is accomplished by rotating the actuators alternately in step-by-step fashion, i.e., by advancing a first leg incrementally, and then a second leg incrementally, and then the first leg, and so on, until both legs are fully mounted on the bushings. Removal of the U-member is achieved by performing that operation in reverse. Such U-members avoid the need to insert and remove the T-connectors as often, thereby lessening the frequency at which it is necessary to manipulate the stiff 600 amp cables. However, in order to access the actuators, it is necessary to remove the ground connector from the bight portion of the U-member. This creates a danger if the system is accidentally re-energized before the ground can be re-established.